1. Field of the Disclosure
The present disclosure relates to a mobile terminal having an antenna device including a plurality of antennas, and particularly relates to a mobile terminal that can prevent the antenna performance from being degraded when a user holds with a hand the body of the terminal in landscape orientation.
2. Description of Related Art
Some exchange carriers (operators) are now starting a service referred to as long term evolution (LTE) as one of high-speed data-communication specifications of a mobile phone. In antenna technology, LTE has the following features.
Namely, LTE is a communication system referred to as multi input multi output (MIMO), and achieves high-speed data communications by using a plurality of antennas to transmit and receive data. A mobile terminal in MIMO system usually includes two antennas. Ideally, it is desirable that the characteristics of the two antennas be equivalent to each other.
Regarding the antenna characteristics, an indicator referred to as antenna correlation becomes a key point. An increase in the numerical value (coefficient) of the antenna correlation (i.e., an increase in the correlation degree) practically causes a decrease in the antenna gain, and the communication speed is decreased.
Consequently, the correlation between the antennas (correlation coefficient) needs to be decreased. However, it is difficult to satisfy the need in a low frequency band such as the 700 MHz band in view of the terminal size.
As one of the methods of decreasing the correlation coefficient, there is a method of providing a parasitic element referred to as a stub on a side of the terminal.
For example, a multi-antenna, which is less influenced by mutual coupling and applicable to a mobile communication system, is proposed in Japanese Unexamined Patent Application Publication No. 2008-17047. The multi-antenna is provided with a plurality of feed elements which are connected to respective feed points provided on a circuit board, and is provided with one or more parasitic elements which are connected to the circuit board in the vicinity of an arbitrary feed point.
Further, the technique of providing the stub on a side of the terminal to improve hearing aid compatibility (HAC) is described in Japanese Unexamined Patent Application Publication No. 2008-17047.